BeLiMIA – Observation of lithium ion cells by merging measurement methods to identify and quantify ageing processes

Project Objective:

The BeLiMIA project is about identifying the essential ageing processes for different cell designs (active material combinations and cell types). To elucidate cell ageing, glass fibre sensors in particular are to be used, which offer versatile possibilities for cell characterisation. The optimisation of these sensors, cell application and sensor data evaluation are therefore the focus of the work.

Work planning:

The HHI is optimising glass fibre sensors for use in cell characterisation. Here, the electrochemically inert glass fibre sensors can be integrated into the interior of the cell and the degree of lithiation can be transferred into an optical strain signal. In addition, age-related mechanical stress formation can be detected. Finally, a correlation between internal and external measurement signal components is to be explored. For the determination of ageing processes, defined material classes and cell designs will be selected at the beginning of the project. ISIT will investigate the dependence of ageing on the load profile (thermal and electrical) by means of cell tests, whereby measurements of sensor cells (reference electrode, glass fibre sensors) will be carried out to identify the main ageing processes, and IFAM will carry out post-mortem analyses. The influence of inhomogeneities through the construction of cells with defined defects and the investigation of the influence of mechanical loads through measurements with glass fibre sensors are to be validated. The quantification of the relationship between load profile and ageing processes as well as cell performance will be carried out with database support, combined with corresponding data analysis on the part of IFAM.

Result utilisation:

The results are published in lectures, publications and posters. In close connection with cell manufacturers and system integrators, the findings obtained are to be implemented directly. In addition, the project results will be introduced into the research cluster “Battery utilisation concepts” as the basis for further projects. The generated data will be made available across clusters via a coordinated database management. The findings on ageing determination can also be used for battery cell research production (FFB) to generate essential findings on ageing prevention or reduction. Due to the expansion of the knowledge base of the participating institutes, high-quality R&D services can be offered to German industry, especially to small and medium-sized enterprises.